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Help voicing an Allen mdac 2110

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  • Help voicing an Allen mdac 2110

    Hi , I recently got an Allen ADC 2100 made in 1985 and would like advice on a number of issues.

    First, the 4” Peerless 8 ohms midrange drivers have rotten foam… what current speaker would be a best drop in replacement? (see pictures)Click image for larger version

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    Second, the original ‘voicer’ left the notes on top of an amp cage, which decayed, from age and heat. Does anyone know about voicing or setting these tiny pots? (see pictures) Click image for larger version

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    If they were all set to ’12 noon’ position…would that be similar to ‘factory neutral’?
    Can DeoxIT or Fader lube be used on these tiny pots? I used DeoxIT on all the RCA interconnects to remove years of oxidation and it made the instrument sound like new.

    It looks like it would be easy to add a reverb unit ahead of the amp, as everything is connected with RCA patch cables…the local Allen tech wants $1000 to add midi to the keyboard only.
    He says it’s not possible to add midi to the pistons, swell or stop tabs… does anyone know about adding midi to everything (As a prep for Hauptwerk.)?

    At this point, my biggest concern is trying to re-voice the stops… the local Allen tech only fixes electrical issues.

    Thanks in advance.
    All advice is greatly appreciated!

  • #2
    I can't speak to your Allen voicing issues, but you might try Parts Express ( for the speaker replacement. A cursory glance at their website came up with several alternatives.



    • #3
      There have been several discussions about the Peerless midrange repairs, the most recent being:

      I'm sure one or more of the many ADC owners/servicers will chime in on the voicing adjustments.

      --- Tom
      Rodgers 660 with additional analog rack sets (practice), 36D/C in digital conversion, Yamaha CVP-107


      • #4
        Peerless speaker foam

        Please read about me rebuilding 46 of these Peerless foam speakers a few weeks ago. Awnelson has supplied you the link to me. It is well worth your time to rebuild them since they are so easy and these are really nice little speakers. Mike


        • #5
          On the USRM (reverb mixer), the pots adjust the amount of signal going to the reverb. J481 on the USRM2 is the output to the Allen ADR4 (digital reverb). You should be able to take this into any quality digital reverb unit. The return goes into J479. Note the reverb unit should be set to 100% "wet", i.e., all reverb on the output, with no input signal directly mixed into the output. The USRM2 handles mixing the reverb signal with the original. If there is a jumper between J319 and J479 remove it (it is for a spring reverb).

          On the main boards, GMTB is Gain, Mid, Treble, and Bass. If there are alterable voices, there are separate voicing adjustments for these as well. Use the attached voicing chart when adjusting the voicing so you know what voices you are adjusting.

          Unless you really need to, I would not adjust the gain.

          The Allen MIDI adapter does not encode/decode stops nor expression--just notes. I don't know of any after-market MIDI adapters for MADC/ADC organs, just for MOS organs.
          Attached Files


          • #6
            Thank you for this amazingly clear and helpful response!

            Is there a control for the tremolos, a way to make them faster or slower and less deep?

            Love the attachment!


            • #7
              There is no adjustment for depth, but there is supposed to be one for speed (unless the Trem3 or Trem4 cards are installed--the tabs to control these are labelled Vibrato). I'm not sure where the regular speed control is located.


              • #8
                Thanks, I just made a 'map' of the current settings on all the voicing controls …

                (They are a widely different from each other, including the Gain settings, some 'G' at the '9' o'clock and others at '3' o'clock).

                Going from left to right, the settings start at '7' o'clock and go "up" to '5' o'clock.
                Do you think a '12' position would be neutral, or is the starting position at '7' neutral?

                My idea is to return to a factory standard first.

                As for the reverb,… the reverb unit I have is a
                Alesis NanoVerb with
                mono R. IN and mono R. OUT …
                mono L. IN and mono L. OUT.
                I see the J481 out and J479 in on the USRM2 board… don’t I need two outs for Ch 1 and Ch2 and two in’s as well? Maybe I need a stereo to mono adapter?

                There are also two smaller boards for each channel labeled
                2110T Ch 1 Gt and Ped and
                2110T Ch 2 Swell.
                Both of these smaller boards have a pot for reverb. (see Picture)
                I had imagined that this is the place to add the Alesis.
                I also thought I could insert the NanoVerb ahead of the amp as long and input and out levels were balanced so as not to clip the signals.

                I am very grateful that you know how to tinker with these Organs!
                I am intimidated by all these controls and afraid of breaking something by overloading a circuit.
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                • #9
                  I think you are better off doing the reverb loop through the URSM boards--they are reverb mixers. The AP boards are audio processors, and they do the expression. Allen looped reverb through the URSM boards when they used a digital reverb on these models, so I would emulate what Allen did. Later MADC boards put all these on a single board, ADC Mixer.

                  Every inexpensive reverb units (talking under $1,000) use a mono processor block for the reverb function, so a stereo input is mixed to MONO to drive the reverb block, so just connect one input to the NanoVerb. The mono reverb output is then sent to both L & R channels, so just connect one output to the reverb return. It does not matter which channel you use unless the manual for the reverb specifies a channel for mono operation.

                  For gain, the standard procedure is to start at the lowest setting (7 o'clock), and move it up slowly. This avoids nasty big noises causing shock and awe to any of your pets, as well as your own ears.

                  Don't set MID, Treble, and Bass at the lowest setting (for starters) as you cannot then cut back any if needed. Start at 12:00.

                  I do not recommend installing the reverb just ahead of the amps. I had a small Alesis reverb unit ones (not a NanoVerb) and threw it out because it distorted the signal. I would not want the clean Allen sound to be distorted by having the dry (un-reverbed) signal distorted by the Alesis electronics. Perhaps your reverb is clean, and it wouldn't matter.


                  • #10
                    Thanks again, I'll follow or advice... bty, I foundthe Alterable 1 and 2 voicing controls.
                    They are labeled 5btmg and 6btmg.

                    I have a tone card call Diapason Test and I just tried setting everything to ‘12’ on both sets.
                    They still have sonic differences … one sounds bright the other sound mellow..
                    Perhaps it’s differences in the speakers themselves or that this instrument is old…
                    I’ll continue to fiddle with these pots to see if I can make them more identical.

                    Thanks to your help, I’m not afraid of touching them!


                    • #11
                      The voicing should be set so that Alterable 1, Alterable 2, and the Great Principal 8' all sound the same. Adjust the Gt. Principal to your liking, and then set the alterable voicing so it matches. It's a good starting point for them.

                      Differences in speakers, speaker position, and whether or not the mid & tweeter in the speaker are good will affect how they sound.

                      On the TG-2 board, there are also 3 potentiometers near the edge for trem speed, percussion secondary-short, and Percussion Primary-Long. The trem speed adjusts the speed for all trems; the Percussion Primary-Long adjusts the decay for the chimes on the Great; the percussion secondary, short, is not used. These pots are kitty-corner from the voicing controls on the TG-2 board.

                      There are also percussion secondary -short and percussion primary - long on the AV-1 (alterable voice) board, and those need to adjusted using percussion voices in the alterables.
                      Last edited by toodles; 03-26-2013, 05:14 PM.


                      • #12
                        Originally posted by toodles View Post
                        The voicing should be set so that Alterable 1, Alterable 2, and the Great Principal 8' all sound the same. Adjust the Gt. Principal to your liking, and then set the alterable voicing so it matches. It's a good starting point for them.
                        Just another viewpoint on voicing the Alterables. I have my 2 Alterables voiced slightly different because it allows me to obtain 2 variations of the same card. I started with voicing as Toodles suggests, but then I make the changes, either in amplitude (Gain), or Bass/Mid/Treble to obtain the best variations out of a card. That way one Alterable can be a solo instrument, while the other can be an ensemble instrument (yes, I know about Alterable F, but that doesn't always obtain the desired result). Once I have re-voiced the Alterables, I then test them with all types of cards to see if there are any objectionable sounds created by my changes (i.e. Strings vs. Flutes, Reeds vs. Diapasons, etc.).

                        If you're just starting, however, I'd suggest following Toodles' suggestion. As you become more familiar with the controls, you'll become more comfortable with making slight changes to suit your tastes.

                        Way too many organs to list, but I do have 5 Allens:
                        • MOS-2 Model 505-B / ADC-4300-DK / ADC-5400 / ADC-6000 (Symphony) / ADC-8000DKC
                        • Lowrey Heritage (DSO-1)
                        • 11 Pump Organs, 1 Pipe Organ & 7 Pianos


                        • #13
                          Hi Michael, When I got this instrument, the Alters were very dissimilar from each other (using the same Diapason etc) and I thought there might be an indication that something was broken.

                          Thanks to Toodles, I found out how to change these pots, showing that nothing is broken.

                          And I agree with you, that setting differences between Alter 1 and Alter 2 are very useful and I have set them to be different, in volume first and brightness second; as they are slightly detuned from each other, potentials for more celeste combos are available.

                          On a different note, this instrument came with very few ADC tone cards but I can buy them off their web-site and I've ask the Allen Company about the sonic difference between cards with the same name but different letters... Mix III A, Mix III B, Mix III C... Gemshorn A, Gemshorn B ... etc. Allen emailed me saying that they don't know how they are different. What cards do you like?


                          • #14
                            Here's the original MADC alterable information from the old order form. It gives some hints as to how the voices differ. On the MADC organs (like yours) the mixtures mostly differ by the starting pitch. You can also get some clues by the first two digits of the card number as that is an indication of the looudness--100 being the loudest (most chorus reeds are 100) and the Aeoline being the softest at 16.

                            Note that the alterable mixtures do NOT break-back, so selection of one over the other sometimes depends on the range where it will be played.

                            The MADC alterables do NOT read the voicing data from the cards--the cards just act as selector switches. This allows things like chiff and percussion to be built into the voice. Pitch is also selected by the card, so it is possible by adding a hole in the right place (or covering one up) to change the pitch by an octave. There's an MADC card layout file on the Allen Owners Group in Yahoo that shows this.

                            If you want alterable voices, I'd order as soon as possible. Allen is no longer making these, and when their current inventory of a card is gone, it will no longer be available from them.
                            Attached Files


                            • #15
                              Check out this ebay auction: http://www.--------/itm/46-Allen-Org...item27d144508b

                              If they go for near the starting price, they are a bargain.